A count of the number of people using public transport vehicles, is desirable, inter alia, so that persons responsible for the organisation of such vehicles can forecast the number of vehicles required to satisfy demand at different periods throughout the day.
In order to be deemed suitable in practise, the apparatus used for counting the number of people using public passenger vehicles must fulfill a number of requirements. One such requirement is that the apparatus must be readily adaptable to different types of buses for example, without requiring excessive assembly work or structural, alterations thereto. The apparatus should be constructed to count passengers whilst they enter and leave the vehicle through the doors thereof. The number of persons entering and leaving the vehicle should both be determined, so that the number of passengers entering and leaving said vehicle between predetermined stopping places along the route of the vehicle can be established. Such an apparatus comprises sensing devices arranged adjacent vehicle doors. As before mentioned, the doors should not have a width such that two passengers may pass therethrough simultaneously side by side. The doors of the majority of buses are already constructed for this purpose. The doors of public passenger vehicles, hereinafter referred to for convenience as buses, whose doors permit the entrance or departure of two or more passengers simultaneously should be provided with a centre partition to prevent this.
In the case of buses provided with two doors, one of which is specifically intended for passenger entrance and the other for passenger departure, it can not reliably be ensured that passengers will enter or leave the bus through the door intended. This is particularly true in passenger peak periods, when passengers are liable to depart from the bus through a door intended for the entrance of a passenger, even through the use of such a door for departure purposes is expressly forbidden. Consequently the passenger-sensing devices must be adapted so that they can sense whether a person is entering the bus or leaving said bus, i.e., they must be adapted to sense in both directions at each door. This requires the provision of two sensing devices for each door.